Characterization and Cytotoxic Evaluation of Bacteriocins Possessing Antibiofilm Activity Produced by Lactobacillus plantarum SJ33

International Journal of Peptide Research and Therapeutics - Biofilm forming pathogens are among the major causes of hospital-acquired infections and are not much affected by antibiotic treatment....     

Genetic analysis of arsenic metabolism in <Emphasis Type="Italic">Micrococcus luteus</Emphasis> BPB1, isolated from the Bengal basin

A highly arsenic-metabolizing bacterial strain was isolated from an agricultural field known for arsenic contamination near Munshiganj (Bangladesh). Based on 16S rRNA gene analysis, the strain was identified as Micrococcus luteus and designated as strain BPB1. Arsenate and arsenite minimal inhibitory concentrations of 650 mM and 7.5 mM, respectively, were observed for strain BPB1, slightly higher than the figures observed in its close relative M. luteus DSM 20030^T. Such observations were consistent with the presence of arsenic-metabolizing genes in the genome of M. luteus. We describe this strain as having an MSH/Mrx-dependent class of arsenate reductase, and an arsenite transporter family in the ACR3(1) group. Besides an intracellular arsenic resistance mechanism, experiments carried out using field emission scanning electron microscopy-energy dispersive X-ray spectroscopy (FESEM-EDS) and Fourier transform infrared spectroscopy (FTIR) demonstrated the ability of BPB1 to sequester arsenate in extracellular polymeric substances on its cell surface.     

Predominance of Roseobacter, Sulfitobacter, Glaciecola and Psychrobacter in seawater collected off Ushuaia, Argentina, Sub-Antarctica

Bacterial diversity in sub-Antarctic seawater, collected off Ushuaia, Argentina, was examined using a culture independent approach. The composition of the 16S rRNA gene libraries from seawater and seawater contaminated with the water soluble fraction of crude oil was statistically different (P value 0.001). In both libraries, clones representing the Alphaproteobacteria, Gammaproteobacteria, the Cytophaga-Flavobacterium-Bacteroidetes group and unculturable bacteria were dominant. Clones associated with the genera Roseobacter, Sulfitobacter, Staleya, Glaciecola, Colwellia, Marinomonas, Cytophaga and Cellulophaga were common to both the libraries. However, clones associated with Psychrobacter, Arcobacter, Formosa algae, Polaribacter, Ulvibacter and Tenacibaculum were found only in seawater contaminated with hydrocarbons (Table 1). Further, the percentage of clones of Roseobacter, Sulfitobacter and Glaceicola was high in seawater (43%, 90% and 12% respectively) compared to seawater contaminated with hydrocarbons (35%, 4% and 9% respectively). One of the clones F2C63 showed 100% similarity with Marinomonas ushuaiensis a bacterium identified by us from the same site.